1. Field of the Invention
The invention concerns self-centering freewheel mechanisms using cams and bearings.
2. Description of the Prior Art
This type of freewheel mechanism, as used in automatic gearboxes in particular, comprises:
the freewheel mechanism proper comprising: PA0 lateral bearings, generally U-shaped in cross-section with a base perpendicular to the axis and two branches, an inside branch and an outside branch. PA0 either there is no fastening between the lateral bearings and the remainder of the freewheel, which makes it difficult to handle the assembly before and during mounting on the vehicle (with the risk of dropping it, and of damaging or losing the bearings), PA0 or the fastening devices linking the bearings and the rest of the freewheel are complex and costly. PA0 the need for a final crimping operation (additional cost), PA0 the risk of local damage to the surface of the bearing in the crimping area, PA0 the fact that crimping of this kind is only feasible on thin bearings.
at least one set of multiple wedging cams, and PA1 spring means (generally a leaf spring) acting on the cams in the direction tending to wedge them to transmit torque;
The combination comprising the freewheel mechanism and the bearings is designed to be inserted between an inside sliding path (shaft) and an outside sliding path (housing).
The function of the freewheel subsystem is unidirectional transmission of torque between the shaft and the housing.
The bearings subsystem is designed only to procure mutual centering of the shaft and housing and to transmit radial forces between the two components.
The freewheel subsystem is arranged so that the cams are normally held in the cage or cages by the spring and can only escape during manipulation of the freewheel before it is mounted on the vehicle.
On the other hand, where the lateral bearings are concerned:
Document FR-A 2 524 093 discloses a device in which the axial fastening of the lateral bearings to the rest of the freewheel uses a "piano string" spring shaped so that it passes alternately between the cams and notches of the bearings to fasten all parts together in the axial direction. It goes without saying that assembling a device of this kind is somewhat delicate.
Document US-A 3 104 744 shows a device in which one of the bearings is fixed to the rest of the freewheel by crimping the rim of the bearing at several points onto the flank of the cage, the fit between the bore in the rim of the bearing and the outside diameter of the flank of the cage being chosen so that there is very little radial clearance between these two parts.
The main disadvantages of this device are:
The objective of the present invention is to eliminate the previous disadvantages, that is to say to overcome the problems explained using simple devices that are easy to manufacture and secure axial fastening together of the bearings and the rest of the freewheel in such a way that it is impossible for the assembly to come apart under normal conditions of handling before and during mounting on a vehicle.